System and Method for Monitoring Pleural Fluid

ABSTRACT

The disclosure is directed to intrapleural air leak detection and monitoring. According to various embodiments of the disclosure, an air leak may be detected utilizing at least one sensor to determine whether fluid extracted from a pleural cavity of a patient includes carbon dioxide and/or a second substance. The second substance may be a foreign substance inhaled by the patient to confirm presence of the air leak. The air leak may be further monitored over a period of time by collecting temporally successive measurements associated with detected concentrations of carbon dioxide. Therefore, tissue damage and recovery may be assessed according to objectively collected criteria.

PRIORITY

The present application is a continuation of U.S. patent applicationSer. No. 14/378,670, now U.S. Pat. No. 9,888,870, entitled SYSTEM ANDMETHOD FOR MONITORING PLEURAL FLUID filed on Aug. 14, 2014, which is thenational stage application of PCT/US13/26362 filed on Feb. 15, 2013,which claims priority to U.S. Provisional Application Ser. No.61/599,724, entitled CHEST DRAINAGE SYSTEM FOR DIAGNOSIS ANDQUANTIFICATION OF INTRAPLEURAL AIRLEAKS, by Dimitrios Miserlis et al.,filed Feb. 16, 2012, which an application of which the currentapplication is entitled to the benefit of its priority date. Theabove-identified patent applications are incorporated herein byreference for all they disclose.

TECHNICAL FIELD

The present disclosure generally relates to the field of pleuralmonitoring and more particularly to detection and quantification ofintrapleural air leaks.

BACKGROUND

Penetration into a patient's pleura or lung parenchyma often results inair leaking into the pleural cavity, referred to as “pneumothorax”. Inaddition to chest injury, disruption of the sealed pleural and thoracicspace may also result from thoracic surgery. Increased intrapleuralpressure from air leakage can cause a lung to collapse. Accordingly, achest tube is often inserted in the pleural cavity to drain fluid andrestore negative pressure in the intrapleural space of patients thathave undergone lung surgery, surgery of adjacent organs, or sufferedinjury to lung tissue as a result of any type of chest trauma.

One method of chest drainage involves a chest tube fluidically coupledto a drainage canister. In some embodiments, the drainage canisterincludes a “3-bottle set-up”, such as the PLEUR-EVAC system produced byTELEFLEX INCORPORATED or the OCEAN WET SUCTION WATER SEAL DRAIN producedby ATRIUM MAQUET GETINGE GROUP. The three bottles may include acollection bottle, a water-seal bottle, and a suction-control bottle.Suction is applied to the pleural cavity to withdraw fluid, includingair “Pneumothorax” from an air leak and liquid “Hemothorax”. Any gaswithdrawn from the pleural cavity enters the collection bottle andpasses into the water-seal bottle where it bubbles through water. Thewater in the water-seal bottle acts as a one-way valve preventing backflow of gas into the chest cavity. Clinicians typically detect air leaksby visually observing bubbles within the water-seal bottle. However, anydetection, measurement, or grading of an air leak is prone toinconsistency caused by observer subjectivity and human error. Theanatomy and physiology of the pleural space and the chest wall can leadto false positive detection of air leaks with current clinical methods(e.g. visual observation of bubbles and chest x-rays). Retained airwithin the pleural space may change position because of pleural spacetissue movements, even when the bronchial and parenchymal leak site hasbeen healed. Movement of retained air results in a delay in the removalof the chest tube and a subsequent increase in the morbidity rate,possible complications, patient discomfort, and unnecessary extension ofhospital stay. Additionally, false negative detection of an air leak mayoccur when small leaks are concealed by collapsing tissues.

Air leaks are one of the most common complications after trauma in thethoracic space, as well as an expected medical problem after thoracicsurgery. Air leaks are a common cause of prolonged hospitalization,adding significantly to the cost of medical care. See Cerfolio R J, BassC S, Pask A H and Katholi C R. Predictors and treatment of persistentair leaks. Ann Thorac Surg 2002; 73: 1727-1730. Furthermore, patientrecovery is difficult to assess with the currently employed detectionand monitoring techniques (e.g. visual observation of bubbles and chestx-rays). Currently, it is customary to establish negative pressuresuction for a specified time following a following a traumatic chestinjury and/or thoracic surgery. This decision is done empirically andresults in the inability to objectively monitor and customize treatmentaccording to the healing/sealing process of the bronchial tree and lungparenchyma.

SUMMARY

The present disclosure is directed to a system and method forobjectively detecting and monitoring an intrapleural air leak. Byutilizing hard results and quantitative measurements, clinicians areenabled to diagnose patients and assess recovery with a higher degree ofconsistency. Accordingly, there is less chance that patients will behospitalized beyond the actual recovery time or require emergentreinsertion of chest tube and readmission due to premature removal.

According to various embodiments, the system includes at least onedetection unit configured to receive fluid from a pleural cavity of apatient. In some embodiments, the fluid includes air or another inhaledsubstance extracted from the pleural cavity utilizing a chest tubefluidically coupled to a drainage canister. The detection unit mayinclude a sensor configured to detect carbon dioxide present in thefluid. The detection unit may further include a sensor configured todetect a second substance present in the fluid. The system furtherincludes at least one processing unit in communication with thedetection unit. The processing unit may be configured to provide a firstelectrical signal when carbon dioxide is detected in the fluid. Theprocessing unit may be further configured to provide a second electricalsignal when the second substance is detected in the fluid.

In some embodiments, the system further includes a user interface incommunication with the processing unit. The user interface may beconfigured to provide an indication that carbon dioxide has beendetected when the first signal is received from the processing unit. Theuser interface may be further configured to provide an indication thatthe second substance has been detected when the second signal isreceived from the at least one processing unit. In some embodiments, thesecond substance is a non-toxically inhaled substance that is foreign tothe human body, such as helium, sulfur hexafluoride, or nitric oxide.Accordingly, detection of the second substance may confirm the presenceof an air leak.

A method of detecting and monitoring intrapleural air leaks may bemanifested by an embodiment of the system described herein. The methodmay include the steps of: receiving fluid from a pleural cavity of apatient; detecting carbon dioxide present in the fluid; providing afirst indication when carbon dioxide is detected in the fluid; detectinga second substance present in the fluid; and providing a secondindication when the second substance is detected in the fluid. In someembodiments, the concentration of carbon dioxide is detected andmonitored over a period of time to quantify an air leak (i.e. tissuedamage) and assess patient recovery (i.e. tissue healing).

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not necessarily restrictive of the present disclosure. Theaccompanying drawings, which are incorporated in and constitute a partof the specification, illustrate subject matter of the disclosure.Together, the descriptions and the drawings serve to explain theprinciples of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The numerous advantages of the disclosure may be better understood bythose skilled in the art by reference to the accompanying figures inwhich:

FIG. 1 illustrates a system for extracting fluid from a pleural cavityof a patient, in accordance with an embodiment of this disclosure;

FIG. 2A is a block diagram illustrating a system for detecting andmonitoring intrapleural air leaks utilizing fluid extracted from apleural cavity of a patient, in accordance with an embodiment of thisdisclosure;

FIG. 2B illustrates a three way adapter for directing a portion ofpleural fluid received from a chest tube along a detection path to atleast one detection unit, in accordance with an embodiment of thisdisclosure;

FIG. 2C illustrates the three way adapter, in accordance with anotherembodiment of this disclosure;

FIG. 2D illustrates the three way adapter, in accordance with anotherembodiment of this disclosure;

FIG. 2E illustrates the three way adapter, in accordance with anotherembodiment of this disclosure; and

FIG. 3 is a flow diagram illustrating method of detecting and monitoringintrapleural air leaks, in accordance with an embodiment of thisdisclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to the subject matter disclosed,which is illustrated in the accompanying drawings.

The pleural cavity maintains pressure that is negative to theatmosphere, which keeps lungs pressed against the chest wall to preventcollapse of a lung during exhalation. The lung may collapse if negativepressure of the intrapleural space is lost or disrupted due to an airleak caused by surgery or any other type of trauma affecting the tissue.FIG. 1 illustrates a system 100 for restoring negative pressure byextracting fluid from the pleural cavity. In some embodiments, thesystem 100 includes a chest tube 102 configured to channel extractedfluid through a conduit 104 to a fluidically coupled drainage canister106. The system 100 may further include a pump 108 (e.g. pneumatic orperistaltic pump) for suctioning the fluid through the chest tube 102.Many chest drainage systems are known to the art including, but notlimited to, the PLEUR-EVAC system produced by TELEFLEX INCORPORATED orthe OCEAN WET SUCTION WATER SEAL DRAIN produced by ATRIUM MAQUET GETINGEGROUP. Accordingly, the foregoing description of system 100 is includedfor illustrative purposes and is not intended to limit the presentdisclosure in any way.

FIG. 2A illustrates a system 200 for detecting and monitoring air leaksutilizing fluid extracted from the pleural cavity by system 100 or anyother chest drainage system known to the art. The system 200 includes atleast one detection unit 202 configured to detect a presence of carbondioxide and/or a second substance in an extracted portion of the pleuralfluid. In some embodiments, the detection unit 202 includes at least afirst sensor 203A configured to detect carbon dioxide and a secondsensor 203B configured to detect the second substance. The secondsubstance may include a non-toxically inhalable substance that isforeign to the human body such as, but not limited to, helium, sulfurhexafluoride, or nitric oxide. In some embodiments, a compositionincluding the second substance, such as FDA approved HELIOX (79% helium,21% oxygen), is presented to the patient for inhalation.

In some embodiments, the one or more sensors 203 of the detection unit202 include diffusion based, spectral based, and/or thermal conductivitybased sensors, operating either in a flow through or discrete mode. Thedetection/monitoring system 200 may include a single-sensor ormulti-sensor configuration. In some embodiments, multiple sensorsoperating as a multi-modal system are contained in one detection unit202. Exemplary sensors that may be at least partially incorporated intothe detection unit 202 include, but are not limited to, carbon dioxideand helium analyzer sensors made by C-SQUARED INCORPORATED, or theVAISALA GM70 CO2 hand-held carbon dioxide meter produced by VAIS ALA, orthe TEKNOKEOMA helium detector (Model #GL-2702-1941), or the helium leakdetector produced by MARKES INTERNATIONAL LTD. The foregoing sensors areincluded for illustrative purposes only. The detection unit 202 mayinclude any sensor or combination of sensors configured forquantitatively determining fluid concentration of carbon dioxide and thesecond substance to enable objective assessment of an intrapleural airleak.

In some embodiments, the one or more sensors 203 may further include ahumidity sensor configured to detect a level of humidity or changes inthe level of humidity at one or more locations along the drainage pathor within the drainage canister 106. The changes in humidity maycorrelate to status (e.g. severity or recovery stage) of an air leak.Accordingly, the humidity sensor may enable an alternative method of airleak detection or may be configured to aid concentration sensors forimproved air leak detection and/or quantification.

Detection of carbon dioxide in the pleural fluid is an initial indicatorthat an air leak exists. However, there are instances where carbondioxide may be detected as a result of an air leak that has alreadyhealed. In addition, the inventors have determined that carbon dioxidedetection with great precision (e.g. detecting a change in carbondioxide concentration caused by a patient coughing) may be required toconfirm the existence of an air leak. Accordingly, detection of thesecond substance allows for improved detection or confirmation of anexisting air leak. Furthermore, by introducing a substance that isforeign to the human body, any detection of the foreign substance in thepleural fluid will accurately indicate the presence of an air leak.

The system 200 further includes at least one processing unit 204 incommunication with the one or more sensors 203 of the detection unit202. The processing unit 204 may include any combination of hardware,software, and/or firmware configured to perform one or more of theprocessing functions or steps described herein. In some embodiments, theprocessing unit 204 includes a computing system defined by a single ormultiple core processor configured to execute program instructions froma carrier medium. The processing unit 204 may alternatively oradditionally include a micro-controller, ASIC, FPGA, and/or acombination of logic gates and discrete components defining anelectronic circuit.

The processing unit 204 is configured to collect information (e.g.Boolean values or measurements) from the one or more sensors 203 of thedetection unit 202 indicating detection of carbon dioxide and/or thesecond substance. In some embodiments, the processing unit 204 isfurther configured to provide at least a first electrical signal whencarbon dioxide is detected and a second electrical signal when thesecond substance is detected. A user interface 206 in communication withthe processing unit 204 may be configured to provide visual and/oraudible indications upon receiving the first signal and/or the secondsignal. The user interface 206 may include one or more audible or visualindicators such as, but not limited to, speakers, illumination sources,or a display unit (e.g. LED, LCD, or CRT display).

In some embodiments, the processing unit 204 is further configured tocollect quantitative information (e.g. volume or percentagemeasurements) associated with a concentration of carbon dioxide and/orthe second substance detected by the one or more sensors 203 of thedetection unit 202. The processing unit 204 may be further configured tocollect temporally successive measurements so that changes in thedetected concentration of carbon dioxide can be monitored over a periodof time. The user interface 206 may be further configured to displayinformation associated with the measurements so that the status or rateof an air leak can be observed and tissue recovery can be assessedaccordingly.

As illustrated in FIG. 1, the one or more sensors 203 of thedetection/monitoring system 200 may be configured to receive a portionof the extracted pleural fluid through a three way adapter 208fluidically coupled to the chest tube 102. It may be advantageous todetect for carbon dioxide and/or the second substance utilizing pleuralfluid from the drainage path to avoid errors due to chemical or physicalalteration which may result after disposition within the drainagecanister 106. In some embodiments, the one or more sensors 203 areconfigured to receive a gaseous portion of the pleural fluid. Forexample, the adapter 208 may divert a gaseous portion of the fluid tothe one or more sensors 203 or the one or more sensors may be disposedwithin a detection chamber when a liquid portion of the fluid is nolonger flowing or has substantially ceased to flow along the drainagepath.

Alternatively, the detection/monitoring system 200 may be disposedwithin the drainage canister 106 or fluidically coupled to an auxiliaryport of the drainage canister 106. For example, the detection/monitoringsystem 200 may be configured to receive a portion of the extractedpleural fluid through a suction port 107 that is configured forinterfacing with the pump 108. In some embodiments, thedetection/monitoring system 200 may be directly coupled to the suctionport 107 (when the pump 108 is removed) or the adapter 208 may bedisposed along the suction path leading to the pump 108. There areseveral mechanisms by which the detection/monitoring system 200 mayreceive pleural fluid. However, the adapter 208 may advantageously allowthe air leak detection/monitoring system 200 to interface with any chestdrainage system, such as system 100, without significant interference.FIGS. 2B through 2E illustrate various embodiments of the adapter 208.

As shown in FIG. 2B, the adapter 208 includes an inflow port 212configured to receive extracted fluid from the chest tube 102 and anoutflow port 214 configured to direct at least a portion of the fluidalong a drainage path to the drainage canister 106. The adapter 208further includes at least one port 210 configured for interfacing withthe detection unit 202. In some embodiments, the adapter includes afirst interface port 210A configured to receive a first sensor 203A anda second interface port 210B configured to receive a second sensor 203B.In some embodiments, the one or more sensors 203 of the detection unit202 are configured to receive a gaseous portion of the fluid when aliquid portion of the fluid is no longer flowing through the adapter208.

FIG. 2C illustrates another embodiment of the adapter 208 allowing aliquid portion of the fluid to flow through the adapter while the one ormore sensors 203 of the detection unit 202 are inserted. The adapter 208may be configured to channel fluid through a first (direct) path betweenthe inflow port 212 and the outflow port 214 until liquid flow ceasesand only gas flow remains. The adapter 208 may include one or morevalves configured to close off the direct path allowing the gaseousportion of the fluid to flow through a second (sensing) path to the oneor more sensors 203 via the one or more interface ports 210 of theadapter 208.

In another embodiment, illustrated in FIG. 2D, the adapter 208 includestwo interlocking structures configured to slide in and out of oneanother. When liquid is flowing through adapter 208 the blocks areconfigured to slide together so that sensors are closed off fromatmospheric air. The blocks are configured to be pulled apart when onlygas flow is present to allow insertion of the first (carbon dioxide)sensor 203A into the first interface port 210A. A septum covering thesecond interface port 210B prevents exposure to atmospheric air when thesecond (second substance) sensor 203B is not in place. The second sensor203B may be configured to receive a gaseous portion of the fluid througha needle inserted through the septum of the second interface port 210B.

FIG. 2E illustrates yet another embodiment of the adapter 208 includingtwo fluidically coupled three way valves. The valves are configured toallow pleural fluid to flow through the adapter from the inflow port 212to the outflow port 214 under normal operation (i.e. chest drainage).The valves are further configured to divert a gaseous portion of thepleural fluid to the one or more sensors 203 of the detection unit 202when the valves are actuated to a selected position. In someembodiments, the valves are mechanically actuated by turning one or moremechanically coupled gears or knobs 216 or by pulling or pushing amechanically coupled shaft. In other embodiments, the valves may bepneumatically or electromagnetically actuated. When the adapter 208 isconfigured for detection by actuating the valves to the selectedposition, the gaseous portion moving through the adapter 208 may flowthrough a first interface port 210A to the detection unit 202 of system200. The gas may be further directed from the system 200 back into theadapter 208 through a second interface port 210B and passed along aremainder of the drainage path (or suction path).

The adapter 208 may further include structural and/or mechanicalfeatures beyond those illustrated by the foregoing embodiments. Theadapter 208 is intended to encompass any three way adapter known to theart. In some embodiments, the adapter 208 is further configured to be a“single-use” adapter. Accordingly, the adapter 208 may be constructedfrom disposable (pre-sterilized) plastic, rubber, and/or metallicmaterials. In other embodiments, the adapter 208 may be constructed fromautoclavable or otherwise sterilizable materials. Furthermore, some orall of the connection ports and tubing utilizing for fluidicallycoupling the system 200 to the adapter 208 may be configured forremovably attaching to one another. For example, the interface ports 210may include tapered male connectors configured to receive tubing of thedetection path. In some embodiments, the interface ports 210 mayalternatively be cooperatively threaded or configured for mechanicallyfastening to the detection path tubing.

As further illustrated in FIG. 2E, the detection/monitoring system 200may be configured for portable use. An enclosure made of lightweightmaterials (e.g. plastic and/or aluminum) may be configured to support orcontain some or all of the detection unit 202, processing unit 204, anduser interface 206 of the system 200. In some embodiments, the system200 further includes a battery or power cell configured to supply powerto the detection unit 202, processing unit 204, and user interface 206.In other embodiments, the system 200 may be configured to receive powerthrough an electrical jack or adapter port. However, enabling the system200 to be utilized without a power cord protruding from a wall outlet orgenerator may improve portability and provide sanitary advantages.

FIG. 3 is a flow diagram illustrating an embodiment of a method 300 fordetecting and monitoring intrapleural air leaks. Systems 100 and 200 aremanifestations of method 300 and all steps or features described withregard to embodiments of systems 100 and 200 may apply to method 300.However, it is noted herein that one or more steps of method 300 may beexecuted via means known to the art beyond those described with regardto systems 100 and 200.

At step 302, fluid is extracted from a pleural cavity of a patientutilizing a chest tube 102 or functionally equivalent device. At least aportion of the fluid, such as a gaseous portion of the fluid, isreceived by a carbon dioxide sensor. At step 304, the carbon dioxidesensor may detect a presence of carbon dioxide in the pleural fluid. Atstep 306, an audible or visual indicator provides a first indicationwhen carbon dioxide is detected. The first indication may notify aclinician that an air leak exists or previously existed.

At step 308, a second substance or a composition (e.g. HELIOX) includingthe second substance is provided for the patient to inhale. In someinstances, a clinician may provide a selected dose of the secondsubstance for the patient to inhale. The clinician may further requestthat the patient cough to induce abrupt exhalation and trigger any airleaks. At step 310, fluid is extracted from the pleural cavity of thepatient after the second substance is inhaled. At least a portion of thepleural fluid is received by a sensor configured to detect the secondsubstance. At steps 312-314, an audible or visual indicator provides asecond indication when the second substance is detected. The secondindication may confirm the existence of an air leak at the time thesecond substance was introduced, thereby enabling the clinician todistinguish between an existing air leak and one that has alreadyhealed.

In some embodiments, the method 300 further includes monitoring theconcentration of carbon dioxide aggregated in the extracted pleuralfluid to assess the severity of an air leak and/or monitor tissuerecovery. At step 316, a plurality of temporally successive measurementsmay be collected utilizing the carbon dioxide sensor. The measurementsare analyzed to determine a change in the concentration of carbondioxide over a period of time. As an air leak persists carbon dioxidemay continue to accumulate in the extracted fluid; however, the rate ofaccumulation will decrease as the tissue recovers. Accordingly, aclinician can determine severity of tissue damage and monitor patientrecovery by observing changes in the detected concentration of carbondioxide over time.

It should be recognized that the various steps and functions describedthroughout the present disclosure may be carried out by a singlecomputing system or by multiple computing systems. The one or morecomputing systems may include, but are not limited to, a personalcomputing system, mainframe computing system, workstation, imagecomputer, parallel processor, or any other device known in the art. Ingeneral, the term “computing system” may be broadly defined to encompassany device having one or more processors, which execute instructionsfrom at least one carrier medium.

Those having skill in the art will appreciate that there are variousvehicles by which processes and/or systems and/or other technologiesdescribed herein can be effected (e.g., hardware, software, and/orfirmware), and that the preferred vehicle will vary with the context inwhich the processes and/or systems and/or other technologies aredeployed. Program instructions implementing methods such as thosedescribed herein may be transmitted over or stored on carrier media. Acarrier medium may include a transmission medium such as a wire, cable,or wireless transmission link. The carrier medium may also include astorage medium such as a read-only memory, a random access memory, amagnetic or optical disk, or a magnetic tape.

All of the methods described herein may include storing results of oneor more steps of the method embodiments in a storage medium. The resultsmay include any of the results described herein and may be stored in anymanner known in the art. The storage medium may include any storagemedium described herein or any other suitable storage medium known inthe art. After the results have been stored, the results can be accessedin the storage medium and used by any of the method or systemembodiments described herein, formatted for display to a user, used byanother software module, method, or system, etc. Furthermore, theresults may be stored “permanently,” “semi-permanently,” temporarily, orfor some period of time. For example, the storage medium may be randomaccess memory (RAM), and the results may not necessarily persistindefinitely in the storage medium.

Although particular embodiments of this invention have been illustrated,it is apparent that various modifications and embodiments of theinvention may be made by those skilled in the art without departing fromthe scope and spirit of the foregoing disclosure. Accordingly, the scopeof the invention should be limited only by the claims appended hereto.

What is claimed is:
 1. A system for monitoring pleural fluid,comprising: at least one detection unit configured to receive fluid froma pleural cavity of a patient, detect carbon dioxide present in thefluid, and detect a second substance present in the fluid; at least oneprocessing unit in communication with the at least one detection unit,the at least one processing unit configured to provide a firstelectrical signal when the at least one detection unit detects carbondioxide, and provide a second electrical signal when the at least onedetection unit detects the second substance; and an adaptor fluidicallycoupled to a chest tube, the adaptor comprising a first path configuredto direct a gaseous portion of fluid received from the chest tube alonga detection path to the at least one detection unit, and a second pathconfigured to direct at least a liquid portion of the fluid receivedfrom the chest tube along a drainage path to a fluidically coupleddrainage canister.
 2. The system of claim 1, wherein the at least onedetection unit comprises a first sensor configured to detect carbondioxide and a second sensor configured to detect the second substance.3. The system of claim 2, wherein the at least one detection unitfurther comprises a third sensor configured to detect a level ofhumidity or changes in the level of humidity at one or more locationsalong the drainage path or within the drainage canister.
 4. The systemof claim 1, wherein the second substance is non-toxically inhalable bythe patient.
 5. The system of claim 4, wherein the second substancecomprises at least one of helium, sulfur hexafluoride, and nitric oxide.6. The system of claim 1, wherein the at least one processing unit isfurther configured to acquire a plurality of temporally successivemeasurements associated with concentrations of carbon dioxide detectedby the at least one detection unit.
 7. The system of claim 1, furthercomprising: an indicator in communication with the at least oneprocessing unit, the indicator configured to provide at least one of anaudible indication and a visual indication when at least one of thefirst electrical signal and the second electrical signal is receivedfrom the at least one processing unit.
 8. A system for monitoringpleural fluid, comprising: at least one detection unit configured toreceive fluid from a pleural cavity of a patient, detect carbon dioxidepresent in the fluid, and detect a second substance present in thefluid; at least one processing unit in communication with the at leastone detection unit, the at least one processing unit configured toprovide a first electrical signal when the at least one detection unitdetects carbon dioxide, and provide a second electrical signal when theat least one detection unit detects the second substance; a userinterface in communication with the at least one processing unit, theuser interface configured to provide a first indication when the firstsignal is received from the at least one processing unit, and provide asecond indication when the second signal is received from the at leastone processing unit; and an adaptor fluidically coupled to a chest tube,the adaptor comprising a first path configured to direct a gaseousportion of fluid received from the chest tube along a detection path tothe at least one detection unit, and a second path configured to directat least a liquid portion of the fluid received from the chest tubealong a drainage path to a fluidically coupled drainage canister.
 9. Thesystem of claim 8, wherein the at least one detection unit comprises afirst sensor configured to detect carbon dioxide and a second sensorconfigured to detect the second substance.
 10. The system of claim 9,wherein the second substance comprises at least one of helium, sulfurhexafluoride, and nitric oxide.
 11. The system of claim 9, wherein theat least one detection unit further comprises a third sensor configuredto detect a level of humidity or changes in the level of humidity at oneor more locations along the drainage path or within the drainagecanister.
 12. The system of claim 8, wherein the second substance isnon-toxically inhalable by the patient.
 13. The system of claim 8,wherein the at least one processing unit is further configured toacquire a plurality of temporally successive measurements associatedwith concentrations of carbon dioxide detected by the at least onedetection unit, and the user interface is further configured to displayinformation associated with the plurality of temporally successivemeasurements.
 14. The system of claim 8, wherein the drainage canisteris configured to receive fluid extracted from the pleural cavity of thepatient by the chest tube, wherein the at least one detection unit isdisposed within the drainage canister.
 15. A method of monitoringpleural fluid, the method comprising the steps of: receiving fluid froma pleural cavity of a patient; directing a gaseous portion of fluidreceived from the pleural cavity of the patient along a detection pathto at least one detection unit; and directing at least a liquid portionof the fluid received from the pleural cavity along a drainage path to adrainage canister; detecting carbon dioxide present in the fluid;providing a first indication when carbon dioxide is detected in thefluid; detecting a second substance present in the fluid; and providinga second indication when the second substance is detected in the fluid.16. The method of claim 15, further comprising: providing the secondsubstance for inhalation by the patient.
 17. The method of claim 15,wherein the second substance comprises at least one of helium, sulfurhexafluoride, and nitric oxide.
 18. The method of claim 15, furthercomprising: detecting a concentration of carbon dioxide in the fluid;and monitoring a change in the detected concentration of carbon dioxideover a period of time.
 19. The method of claim 15, further comprising:directing fluid received from the pleural cavity of the patient alongthe drainage path to the drainage canister, wherein at least onedetection unit is disposed within the drainage canister.